Booster seat



FIG. 1 is a perspective view of a booster seat showing our design;

FIG. 2 is a front elevation view thereof;

FIG. 3 is a rear elevation view thereof;

FIG. 4 is a right side view thereof;

FIG. 5 is a left side view thereof;

FIG. 6 is a top view thereof; and,

FIG. 7 is a bottom view thereof.

The broken lines form no part of the claimed design but show an environment in which the design may be used. 

CLAIM The ornamental design for a booster seat, as shown and described. 